Cellulosic fiber-containing textile materials such as cotton cloth have been employed since ancient times. However, the combustibility of these textile materials has inhibited their wider use in certain instances. A great number of flame retardants have been proposed for use with cellulosic textile materials, but these flame retardants suffer from one or more disadvantages.
A major disadvantage of many prior flame retardants is their lack of wash fastness or durability, by which is meant that while they initially render the cellulosic textile material flame retardant, such flame retardancy disappears after one or more household launderings, especially in hard water. This phenomenon is described by O'Brien in "Cyanamide-Based Durable Flame-Retardant Finish for Cotton," Textile Research Journal, March 1968, pp. 256-266. This article describes the treatment of cellulosic textile materials with flame retardants of cyanamide and phosphoric acid. However, the flame retardants disclosed therein by O'Brien are not resistant to hard water washing. similarly, East German Pat. Nos. 15,357 and 18,253, and Schiffner et al in Faserforsch u. Texiltech., 14, (9), 375-86 (1963) describe specific attempts to impart flame resistance to textile material with certain flame retardants, including combinations of urea or dicyandiamide with chloromethyl phosphonic acid, or urea with hydroxymethyl phosphonic acid, which combinations may also not be resistant or durable to repeated cycles of hard water washings, or which may unduly degrade the physical strengths of fabrics.
Other disadvantages include the relatively large quantities (high add-on) which may be necessary in order to impart flame retardance, and the undesirable alternation of other properties of the cellulosic textile material such as hand, color, and susceptibility to dying.
Also, many flame retardants are incompatible with commonly employed creaseproofing agents; in the past this limitation has discouraged use of flame retardants in conjunction with a creaseproofing operation so as to yield a textile material which is both flame retardant and wrinkle resistant. In addition, some flame retardants can cause undue shrinkage of the treated fabrics.
An efficacious process for rendering cellulosic fiber-containing textile materials flame retardant is shown in British Pat. No. 1,317,468. As disclosed therein, the textile material is contacted with certain alkyl or haloalkyl phosphonic acids (or their half esters) in conjunction with an amino compound such as cyanamide, methylolated cyanamide, methylolated melamines, methylolated cyanoguanidine or mixtures thereof, to deposit thereon a flameproofing amount of the phosphonic acid with the amino compound.
The search has continued for commercially acceptable processes for imparting flame retardancy to cellulosic fiber-containing textile materials.